FIGURE 5.

Models for the coordination of editing and splicing by the transcription machinery. (R/G site) Editing and splicing of the GluR-B R/G substrate. During transcription in the presence of the CTD, splicing is delayed until after R/G editing. After intron removal, the majority of the mRNAs are therefore edited. In the absence of the CTD, there is competition between splicing and editing that prevents editing. After intron removal, the majority of the mRNAs have escaped editing. (Q/R site) Editing and splicing of the GluR-B Q/R substrate. During transcription in the presence of the CTD, splicing is delayed until after Q/R editing. The A-to-I change at the Q/R site has a positive effect on splicing. After intron removal, most of the mRNAs are therefore edited. In the absence of the CTD, editing and splicing occur independently. After intron removal, mRNAs will have escaped editing, although a subset of the molecules will be edited.